1. Field of the Invention
The present invention relates to improved apparatus for repairing indentions in a rigid skin, and more particularly, but not by way of limitation, to an improved apparatus for repairing dents in the metal skin of the body of an automobile.
2. Description of the Prior Art
In the construction of vehicles and the like, an outer skin surface often forms a body so as to enclose the operative parts of the vehicle, and to function as the outer skin in the wind stream created while the vehicle is moving. Examples of such vehicles are automobiles, trucks, travel trailers and airplanes. In the use of such vehicles and the like, the outer skin may be exposed to accidental damage brought about by normal usage in traffic, and may incur damage from weather elements, including hail, snow and rain. These are examples of the abuse generally created by external forces brought against the skin surfaces of vehicles and the like. As a result thereof, it often happens that indentations, or dents, are caused in the facade or skin surfaces, and it is often necessary or desirable to restore the skin surfaces to their original shapes.
Repair to outer skin surfaces, such as automobile body surfaces, is performed by a number of techniques. If damage is very extensive, it may be necessary to remove part of the outer skin, such as for example a fender, and to replace the removed part with a new or rebuilt component. If the body skin is dented, the dented area may be built up by adding material to fill in the dent, and surface finishing techniques are used to match the appearance of the repaired areas with the appearance of the surrounding surfaces. Yet another way of repairing dents in body skin surfaces is to force the dented area back to its original shape, or at least to approximately its original shape, by applying a force against the dented area in a direction generally opposite to the direction of impression of the dent.
It is a relatively easy matter to repair dented portions of a body skin when it is possible to have free access to the back or dent protrusion side of the body skin. However, it is a different matter when the body skin is constructed in a manner so as to enclose a space wherein it is impracticable to work the rear side of the body skin. In this case, techniques have been worked out to pull the dent from the side of impression by attaching a pulling member to the area of indentation, such as by the use of a welding rod or the like.
Several prior art patents that teach apparatus practicing techniques of dent straightening are U.S. Pat. No. 2,949,144, issued to Dredske et al; U.S. Pat. No 3,545,250, issued to Jones; U.S. Pat. No. 3,187,538, issued to Painter; U.S. Pat. No. 3,091,983, issued to Kliss; U.S. Pat. No. 2,799,190 issued to Awot; U.S. Pat. No. 2,957,376, issued to Parisi; U.S. Pat. No. 2,749,795 issued to Boykin, Jr.; U.S. Pat. No.3,066,719, issued to Selnick; and U.S. Pat. No. 2,605,658, issued to Sanchez.
While the prior art has generally met with success in repairing indentations in the body skin of automobiles and the like, usually the machinery or apparatus to perform the same has been bulky, or at best, rather awkward to manipulate. This is especially true when a vehicle has a large number of indentations, such as when an automobile has suffered the effects of multiple indentations caused by the striking thereof by falling ice or hail. Not only must a large number of impressions or dents be straightened, it is generally to be expected that the body skin is covered by paint or by a vinyl covering, such as in vinyl-topped automobiles, in which case it is undesirable to mar the surface as is generally required by most prior art devices.
Yet another problem with the straightening of dents is that of overpulling the indented portion wherein there is caused a positive protrusion after pulling the dent back to the surface. In other word, the metal skin forming the dented portion is plastically deformed so that it is not returned to its original shape.